Sorry to hear that you're having trouble. The evaluation version is fully functional, so this shouldn't be happening. We've not seen this before. Are you saving to a local folder that you know you have permissions for? Or is it a network share?

What can you see in the "Save documentation to" field at the bottom of the SQL Doc app? If you could email me a screenshot of the error (david dot atkinson @ red-gate.com) it should help me troubleshoot it.